1. Field of the Invention
The present invention relates to a substrate processing apparatus.
2. Description of the Related Art
A substrate processing apparatus includes a chamber including a process chamber for performing a desired process such as an etching on a substrate by an introduced gas, and an exhaust chamber for evacuating a gas in the process chamber. A deposit is generated accompanying the etching process. The generated deposit adheres on an inner wall of the chamber, and becomes a cause of generating dusts such as particles.
Therefore, a deposition shield is provided near the inner wall of the chamber, and the inner wall is covered with the deposition shield in order to prevent the deposit from adhering on the inner wall of the chamber. The deposition shield is replaced when the inside of the chamber is cleaned, thereby preventing the dusts from being generated inside the chamber.
In the meantime, when performing a desired process by the substrate processing apparatus, a pressure inside the chamber needs to be controlled so as to agree with process conditions. To achieve this, as disclosed in Japanese Laid-Open Patent Application Publication No. 2010-251464 and Japanese Laid-Open Patent Application Publication No. 2009-123946, measuring the pressure inside the chamber by using a pressure gauge installed outside the chamber and controlling the pressure inside the chamber based on the measured pressure value are performed.
However, a position where the deposition shield is arranged changes depending on a process performed in the chamber. Moreover, a distance may be created between the deposition shield and the inner wall of the chamber depending on the position where the deposition shield is arranged, and a space on the exhaust chamber side may be created between the deposition shield and the inner wall of the chamber.
In this case, when the pressure inside the process chamber is measured by using the pressure gauge outside the chamber, the pressure inside the process chamber is measured through the space on the exhaust chamber side. As a result, the measurement by the pressure gauge is influenced by the pressure of the exhaust chamber, and the measured value by the pressure gauge may take a value deviated from the actual pressure in the process chamber.